A fluid-based hyper/hypothermia system is disclosed, for example, in DE 696 34 572 T2. Fluid-based hyper/hypothermia systems that use a temperature-controlled fluid to raise the temperature of a human or animal body, body part or organ to above the normal core body temperature or to lower it to below the normal core body temperature require a temperature control device that provides a temperature-controlled fluid to accomplish the desired change in body temperature. The temperature of the fluid must be controlled in the temperature control device in accordance with the quantity of heat to be supplied to or removed from the body. The fluid, for example, must be heated or cooled and then maintained at a predetermined temperature.